C+S December 2022 Vol. 8 Issue 12 (web)

Ulteig Engineers, Inc. CDOT I-70 Bridge Replacement of F-13-S-Minor

Project Location: Silverthorne, Colorado Category: Transportation + Infrastructure Started: March 4, 2020 Completed: September 30, 2022 Project Team: Owner- Colorado Department of Transportation; EOR- Ulteig Subs- San Engineering; Pinyon Environmental; Collective Marketing; BGC Engineering; Emprise Concepts; Farnsworth Group; Contractor- Kraemer NA Project Accreditations: 100 Year Design Life

Project Summary: This project was delivered using the CM/GC delivery method on an accelerated schedule with the contractor providing input throughout the design process. The final design called for two buried bridges consisting of a cast-in- place deck on prestressed adjacent concrete boxes bearing on abutments supported by micropiles. In front of the abutments, soil nail walls minimized the height of the abutment stem walls, which reduced the amount of excavation required. This also reduced impacts to I-70 by shortening the duration of construction phases by building most of the soil nail walls while the bridges were under live traffic. CDOT hasn’t often used micropiles on bridge replacement projects, but they were ideal for the mountainous conditions expected at over 10,000 feet of elevation. This project was also a major roadway reconstruction project necessitating the shift of I-70 westbound 10 feet to the south due to an adjacent landslide. Phasing was a crucial consideration throughout design. The final design called for a four- phase solution with an initial phase shifting traffic away from the median while preparing to overbuild in the median during Phase 2. In Phase 3, traffic was shifted onto the structure built in Phase 2, where the remaining bridge is constructed. In Phase 4, the soil nail walls, grading, and final paving will be completed. The phasing solution allowed for three lanes of traffic to be maintained uphill throughout construction, which was critical given the heavy traffic at 36,000 ADT. Due to the complex phasing and topography, earthwork quantities were presented on a per-phase basis, allowing for greater transparency during construction regarding the movement of earth. The design phase of this project was completed in 10 ½ months after kicking off in March of 2020 just prior to COVID19 lockdowns being implemented. This project was one of CDOT’s first to utilize ProjectWise Share and Bluebeam Revu. Utilizing these pieces of software, we created a collaborative virtual work



December 2022

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